Tow target carrier



Sept. 26, 1950 c. G. TRIMBACH TOW TARGET CARRIER 9 Sheets-Sheet 1 Filed March 21, 1949 Sept. 26, 1950 c. a. TRIMBACH TOW TARGET CARRIER 9 Sheets-Sheet 3 Filed March 21, 1949 INVENTOR. (If/ 7 72/443964 Hiram/5 liilllllllllllll Sept. 26, 1950 c. e. TRIMBACH TOW TARGET CARRIER 9 Sheets-Sheet 4 Filed March "2 1*, 1949'- M m N v MW Flint/n75- Sept. 26, 1950- c. G. TRIMBACH 2,523,738

TOW TARGET CARRIER Filed March 21, 1949 9 Sheets-Sheet 5 INVENTOR. at? 4. 72/4/59! IIIII/Vl/ Sept. 26, 1950 c. G. TRIMBACH 2,523,738

' TOW TARGET CARRIER Filed March 21, 1949 9 Sheets-Sheet 6 H I I lvaen t/J- Sept. 26, 1950 c. G. TRIMBACH TOW TARGET CARRIER Filed March 5211 1949 9 Sheets-Shet a mar/#24: 772667 "7 INVEN TOR. Z 1.67% 4 79/0/84! MIRA/13- Sept. 26, 1950 c. G. TRIMBACH TOW TARGET CARRIER Filed March :21, 1 949 9 Sheets-Sheet 9 IN V EN TOR. (/[Md 79/4/5754 lrrai/l/J- Patented Sept. 26, 1950 TOW TARGET CARRIER Clem G. Trimbach, Eggertsville, N. Y., assignor to the United States of America as represented by the Secretary of the Air Force Application March 21, 1949, Serial No. 32,696

Claims. 1 l

The present invention relates to means for carrying, discharge and release of aerial tow targets from high speed aircraft and including means to permit actuation of the equipment by the pilot through remote control.

The towing of aerial targets at high speed by single seat fighter aircraft while very desirable raises many problems not present in releasing and towing targets from slow speed cargo aircraft where crew members other than the pilot are available to operate the release and towing equipment. Space in the fuselage is insufficient for storage of the targets and because of shock loads the targets cannot be released and exchanged by allowing the targets to slide along the cable to actuate automatic release and exchange mechanism at the end of the tow cable.

In one experimental system the targets were housed in containers mounted under the wing on opposite sides to the aircraft and discharged by gravity through the rear of the container. The targets were each provided with individual tow cables which were disconnected from the aircraft when individual targets were to be released and dropped to the ground. This system had the disadvantage of imposing high shock loads on the aircraft, excessive weight due to the individual tow cablesrequired, liability of cable fouling during discharge and generally in loss of the cables due to tangling after the targets reached the ground.

In accordance with the present invention the tow targets are housed in a streamline container or carrier preferably mounted by struts below the fuselage of an aircraft such as a fighter plane. The carrier is provided with a bottom opening closed by doors which may be automatically released to allow a target to drop therethrough. A winding reel having a tow cable thereon is positioned in the after portion of the carrier, the reel being friction braked during unwinding of the cable and driven by an electric motor during the reeling operation. The respective targets are provided with explosive ruptured frangible connecting rings mounted on a guide and adapted upon discharge of a target to engage a hook on the tow cable. The aerodynamic drag of the target then causes the cable to be slowly payed out avoiding any heavy shock load. The targets are released from the end of the tow cable by electrically det-onating the explosive in the connecting ring to thus drop the target. An automatic emergency release is also provided for disconnecting the cable from the winding drum so that the cable may be dropped if the necessity for such action arises.

,All of the functions of automatically discharging the targets sequentially, releasing the same and winding in the cable after each release is controlled by a pilot actuated stepping switch having indicating means indicating which operation is being performed and provides for the operations being accomplished only in a predetermined sequence. By means of a separate switch the pilot may effect emergency release of the tow cable when necessary.

It is accordingly an object of this invention to provide a carrier for aerial tow targets comprising a housing adapted to be mounted on a high speed aircraft, the carrier having means for housing the targets and automatically sequentially discharging the same, the carrier having a power actuated reeling mechanism positioned therein such that the targets are coupled to a tow cable on the reeling device after discharge to cause paying out of the cable and the latter being reeled after release of a target being towed to effect a target exchange upon discharge of a succeeding target, the means for coupling the target to the tow cable being an explosive device electrically actuated by energizing the tow cable, there being a remote control system controlled by the pilot for automatically effecting target discharge, target release and reeling in a predetermined sequence.

It is a further object of the invention to provide in a tow target carrier and release system of the character described to provide indicating means to indicate the system operation last performed.

It is another object of the invention to provide, in a tow target system of the character described, a means controlled by the pilot for automatically disconnecting the tow cable from the reeling device to permit the cable'to be dropped in case of an emergency.

Other objects and features of the invention will appear by reference to the detailed description hereinafter given taken in conjunction with the appended drawings in which:

Fig. 1 is a perspective view illustrating the mounting of the carrier on a fighter airplane and. the manner in which a target is towed in flight;

Fig. 2 is an isometric view partly in section illustrating the general construction of thecarrier;

Fig. 3 is a front view of the carrier or housing of Fig. 2 with the nose section and support removed;

Fig. 4 is a view, partly in section, illustrating a solenoid actuated mechanism for releasing the external doors on the carrier;

Fig. 5 is a view similar to Fig. 4 illustrating a similar mechanism employed in releasing internal partitions or tow target supports;

Fig. 6 is an isometric view illustrating the automatic tow line reeling mechanism mounted on the carrier structure;

Fig. '7 is a side elevation partly in section fur- 3 ther illustrating the reeling device shown in Fig. 6;

Fig. 8 is a top plan view partly in section illustrating the reel driving and braking mechanism;

Fig. 9 is a fragmentary view illustrating a solenoid for actuating an automatic tow cable release shown in Fig. 8;

Fig. 10 is a top plan view partly in section of the solenoid actuator of Fig. 9;

Fig. 11 is a View illustrating details of the explosive release coupling between a tow target and the tow cable;

Fig. 12 is a general circuit diagram of the tow target control system;

Fig. 13 is a front elevation view of the control box and indicator of the control system of Fig.

Fig. 14 is a fragmentary circuit diagram illustrating the portions of the circuit diagram, Fig. 12, operative in discharge of the first target;

Fig. 15 is a fragmentary circuit diagram illustrating the circuit components of Fig. 12 operative in explosively releasing a target;

Fig. 16 is a fragmentary circuit diagram illustrating the components of the control system of Fig. 12 employed in control of the reeling in of the cable after target release; and

, Fig. 17 is a fragmentary circuit diagram illustrating components of the circuit of Fig. 12 employed in control of th discharge of targets housed in the upper part of the carrier.

Referring to the drawings, Fig. 1 illustrates a conventional fighter aircraft I capable of speeds in excess of three hundred miles per hour and having the tow target carrier or housing generally indicated by reference numeral 2 positioned below the airplane fuselage and suitably supported by struts 3. A flexible metal tow cable I56 extends from the carrier 2 and connects by means of an explosive rupturable coupling to the i bridle B1 of a conventional banner type aerial tow target T1 preferably incorporating metallic fibers so as to serve as a reflector for a tracking radar.

As seen in Fig. 2 the tow target carrier, generally indicated by the reference numeral 2, comprises a generally cylindrical sheet metal container 4 made from light aluminum alloy sheet or the like. The container is provided with a rigid central vertical wall or partition 5 suitably stiffened by vertical stiffener members 6, the outer shell of the container being suitably supported from the central partition by means of circular stiffening rings 1. At its forward end the carrier 2 is provided with a circular ring 3,

strengthened by tubular members 9, the ring 8 serving as an attachment point for hinges ll of doors i and I8 which cover the open bottom of the carrier 2 and are movable outward similar to conventional bomb bay doors, note also Figs. 3 and 6 for discharge of targets from the interior of the container. Each of the doors Ill and [0 are provided with lever extensions I2 which are connected by means of cables I3 to springs l4, only one of which is shown in Fig. 2, for retracting the doors I0 and ID. The weight of the tow targets resting on the doors is sufficient to open the same after release of suitable latching means and the springs I4 are of sufficient strength to close the doors against the effects of air resistance.

As seen in Fig. 2 internal transverse partitions l and I5 are hinged to the vertical wall or partition 5 by means of hinges such as indicated at l6 so that the internal partitions may be 4 dropped, such as in the position shown for partition IS in Fig. 3, permitting a target supported above the partition to drop into the lower portion of the carrier housing 4 and to be subsequently discharged therefrom by opening of door IE or ill. The hinged partitions l5 and E5 of Fig. 2, when latched in position, serve as a means for supporting targets thereabove and when the doors [0 and i0 are closed two additional targets may be housed within the carrier 2. The target positions are indicated in Fig. 3 by the target indicia T2 to T4, inclusive, the targets being of the banner type and wound in a roll and extending throughout a considerable portion of the length of the carrier.

As seen in Fig. 2 the carrier may be closed at its forward end by means of a dome shaped streamlined nosepiece l8 which is removably secured by means of a fastener stem 29 and fastener element 20 which is mounted at the intersection of the supporting tubular structure 9. (Note Fig. 3.) The carrier 2 is also inclosed at its rear end by a removable plastic housing I8 which must be made of an electrical insulating material to avoid accidental contact with highvoltage electricity, as will be subsequently explained. The rear portion of the carrier 2 also serves as the mounting or support for a reeling structure Hill to be later described.

As seen in Figs. 2 and 3 the latching mechanism for the doors Ill and H) is generally indicated by the reference numeral 25 and comprises two identical, but separately actuated, latching mechanisms only one of which is shown in Fig. 4 and will now be described.

Referring to Fig. 4, the door latching mechanism generally indicated as 25 has one of the two door latching mechanisms illustrated as including an electrical spring biased solenoid 26 of conventional construction supported from a vertical mounting wall 27 and having a plunger element 28 which is normally extended by the spring within the solenoid 26 and retracted to the left by electrically energizing the solenoid. The plunger 28 is pivoted at 29 to a link 30 which in turn is pivoted at 5! to a lever 32 which in turn is rockable about a pivot 33 provided in a bracket 34 rigidly mounted on a front supporting bracket 35. The lever 32 is provided at its upper end with an arcuate shaped cam 36 which normally is in engagement with a projection 31 on one arm of a bell crank 3? which is pivotally supported at 38 from the bracket 34. The lever arm 3'! has an arcuate recess therein as shown at 39 such that when cam 36 is rotated in a clockwise direction until a lower edge of the cam is in register with the recess 39, lever 37 can then rock about its pivot 38.

The bell crank 37 has a horizontally extending arm 50 which terminates in a toe portion 4| which is urged by means of a rat trap spring 42 into camming engagement with an inclined surface 43 of a lever 44 pivotally supported at 45 from bracket 34. The lever 44 has a laterally and downwardly extending fork 46 in which an arcuate latch member QT is pivoted at 48. The latch 41 is slotted at 49 to receive a guide pin 50 and is urged by a biasing spring 5| to extend in the latching position as illustrated. the latch entering an aperture 52 in the end of a tubular member 53 secured along the outer edge of door By energizing solenoid 26 plunger 28 will be retracted to the left from the position as seen in Fig. 4 and through link 30 and lever 32 will weight'of the door Ill acting on latch 4'! can' then rotate lever 44 and by camming action on toe il rotate bell crank arm id until the latch 4! clears the tube 53 unlatching the door It and permittingthe same to drop due to the weight of a target resting thereon. Retraction of door it] by means of the action of retractionspring M (Fig. 2) causes the latch member M to be cammed inward against the resistance of spring 5| until the latch is registered with the aperture 52 and the door is again locked. The structure so far described is effective to latch and support only one end of the target release doors and supplemental latching mechanism for th rear end of the doors will now be described.

The lever 31 is pivotally connected as at 54 to an extension rod 55 and which extends within the carrier casing 4 the length of door iii and the far end of the rod 55 is pivotally connected as at 56 to a latching lever 5i pivotally supported at 58 by a bracket 59 from the rear end wall 59 of the target carrier 2, the end Wall construction being clearly shown in Fig. 6. The force transmission rod 55 serves to actuate thelever 51 simultaneous with movement of lever M andjlever 5'! is provided with a forked extension 5!, arcuate latch 62, spring 63 and other parts corresponding to elements 46 through 5!, inclusive, associated with lever 99. Thelatch 52 is ada'pted'to enter an aperture 5 1i in tube 53 and cooperates in latching door It] in the same manner as latch fill It will be noted that the contacting cam surfaces ill and 43 never become disengaged so that upon deenergization of solenoid 26 the door 59 can be retracted by spring M, Fig. 2, and moved into latched position by 'camming the latches t! and 62 against the resistance of biasing springs 5i and 93, respectively. The door latching mechanism employed with the other lower door I9, Figs. 3 and 6, is identical to that shown in Fig. 4, and hence need not befurther described except that in the circuit diagrams the door solenoid actuator for the door Iii will be indicated by reference character 26'.

The latching mechanism for the interior hinged partitions l5 and 85, Fig. 2, as indicated in general in Fig. 3 by the respective reference numerals 95 and 65'. Each of these latching mechanisms is identical in construction and only one such mechanism is illustrated and described in conjunction with Fig. 5. Referring to Fig. 5, the interior door or hinged partition latching mechanism, as generally indicated by reference character 95, is seen as including a conventional spring biased electrical solenoid 66 mounted on a suitable vertical bracket El and having a plunger 68 which is drawn inward from the position shown in Fig. 5 upon electrically energizing the solenoid 65. The solenoid plunger 58 is pivotally connected at 69 to a link it! which in turn isv pivotally connected as at H to the lower end of the lever i2 pivoted at '63 to a bracket M mounted on a suitable vertical mounting plate l5 secured portion Bl which is in camming engagement with an inclined surface 82 on a lever 83 pivotally mounted at 94. The lever 83 is provided with a latching detent 85 which is adapted to enterv the open end of a tubular memberv as secured along the outer edge of droppable partition l5.

Supplemental'latching means are provided in which an elongated force transmission rod 89 is pivotally connected at 88 to the bell crank arm ll with a biasing spring 99 which urges the lever T! in a direction to cause the bell crank arm 86 to cam the latching lever 83 in the latching direction and also tensions rod 89. The rod 89 is pivotally connected at its other end as at 9! with a latching lever 92 having a latching'projection 93 which is adapted to enter the rear open end of tube 89130 additionally support andlatch the interior door or partition l5.

The operation of the latching mechanism of Fig. 5 is similar to that of Fig. 4 such that with the parts in the position shown, energizing solenoid 66 causes plunger 68 to retract and through link iii and lever l2 rotates cam 16 until the same registerswith recess iii. The weight of a target resting on partition i5 is then suflicient to cause rotation of latching levers 83 and 92 in oppositedirections against the resistance offered by biasing spring 99 to direct tension force in rod 89 and to force produced by cam action at surfaces 82 and 8! transmitted through bell crank arms 89 and Ti to the spring90 so that the latching elements emerge from latching engagement with the tube 86 and allow the partition to drop.

When the partition or door It is dropped after it moves approximately fifteen degrees a switch (shown in the wiring diagram) is actuated to deenergize the solenoid 66 and spring 93 returns the parts to the latched position and the parti tion 15 can be relatched by manually raising the same on the ground and manually retracting the solenoid plunger so that the tube 89 may cam the latching detents apart and permit the same to enter the tube ends.

Since the latching device generally indicated as 65" Fig. 2 is identical to that of the device of Fig. 5 both as to structure and operation, further description of the same is unnecessary except that the solenoid actuator thereof will be subsequently identified in the general wiring diagram, Fig. 12, by the reference character 66.

Reeling mechanism As previously described with reference to Fig. 2, the reeling mechanism generally indicated by reference numeral I00, is employed for the purpose of target exchange, the reeling mechanism being best understood from the disclosures of Figs. 6, 7 and 8. As seen in Fig. 6, the reeling mechanism comprises insulating mounting brackets Nil suitably supported from the rear end wall 69 of the target carrier, the insulation serving to electrically isolate the reeling structure from the carrier body and airplane, since during target release the reel is subjected to an electrical potential of thirty thousand volts with respect to ground. The reeling structure proper comprises a pair of side plates Hi2 and M3, respectively, secured by bolts or the like to insulated mount ing brackets IEI. An electric driving motor H15 having a built-in gear reduction issecured by means of bolts It! to the end wall 502, and as seen in Fig. 8 includes a driving shaft Hi6 suitably journalled in the end wall m3 in a manner hereafter described for driving the reeling drum. The

motor housing is provided with lugs I08 which by means of bolts I09 support an inwardly directed flange member I I which serves as a seat for a ball bearing II2. A similar inward turned flange III of end wall I02 serves as a seat for the similar bearing H3. The outer races of the bearings IE2 and H3 have bearing rings I I4 and H5, respectively, pressed thereon which in turn are secured to the cylindrical winding drum or reel H6. The cable receiving winding drum II6 has a flanged drum I I8 secured at one end thereto, which drum is secured to a flange sleeve I20 arranged concentric with shaft I06 and pinned to the shaft by means of a taper pin I2I which also serves to mount a bevel gear I22 on the outer end of the sleeve I20. Rotation of motor shaft I06 through sleeve I20 is thus enabled to drive the drum I I6 to wind in cable.

The in-turned flange member I I0, which serves as a bearing support for the drum bearing H2, is pierced by longitudinally extending cooling apertures, and its periphery I25 is splined to secure alternate plates of a friction brake generally indicated at I26, the other pairs of plates being suitably splined to the drum II6. Suitable friction facing is applied to alternate plates of the friction brake which is maintained under compression by means of a loading spring I21'suitably supported by projections on an abutment plate I28 which abuts an internally threaded ring I29 and which is adjustable upon an externally threaded inwardly directed flange I30 integral with drum member I I8 so that the spring loading on the brake may be adjusted through a suitable aperture in the drum H8 to apply a constant braking force on the winding drum. The braking force applied by brake I26 is just sufiicient to enable the tow cable to be payed out with a target attached at a safe speed but not unduly overload motor I during the reeling operation.

As seen in Fig. 8 the pinion gear I22 meshes with a smaller pinion I3I secured to one end of the shaft I32 which is rotatably supported in a bearing journal I33 secured to the end frame member I03. The shaft I 32 at its outer end is journalled in a suitable bracket I34 and has a worm I35 thereon which meshes with a worm wheel I36 and is adapted to drive a shaft I31 journalled at each end by means of bearings I38 formed in the end frame members I02 and I03. The shaft I39 is provided with right and left hand intersecting threads I39 thereon to form a conventional level wind for a cable guide head I40, which is provided with a pin, not shown, which engages an alternate one of the threads I39 in each direction of traverse relative to the shaft I31. The guide head I40 is provided with a guide pulley I42 over which the tow cable passes.

As seen in Fig. 6 the cable guide head I40 is provided with bearing guides I43 and I44 which are slidable upon parallel tubular guide members I45 and I46 respectively which are secured transversely of the cable drum II6 to the end frame members I02 and I03. It will be seen that during winding and unwinding operations of the drum II6 the shaft I32 will drive shaft I31 to cause the winding guide I40 to reciprocate back and forth on the guides I45 and I46 so that the cable lays are wound, one adjacent the other in uniform layers. This level winding mechanism is of the type well known in the art whose operation is believed to require no further explanation.

As seen in Figs. 6 and 7 the cable guide I40 is provided with an outwardly projecting hollow stem I49 which is made of insulating material having a suitable rectangular base for attachment to the body of the guide member I40. The stem portion I49 is hollow and serves as a guide for the tow cable I50 which passes therethrough and which is provided at its outer ends, as shown in Fig. 6, with a stop member I5I upon which is secured a conventional snap hook I52 to which the target bridles are secured. A spring I54 mounted concentric on the guide stem I49 engages a collar I55 which is actually slidable on the guide stem and is retained by means of stops I56 from slipping off the end of the guide stem I49. The spring I54 and collar I55 serve as a means to push explosive coupling members C1 to C4, inclusive, up against the stops I56 so that the coupling members may be respectively pulled over the stops off the guide member I49 and onto the cable I50 whenever a respective target, connected to the coupling member by a respective bridle, B1 to B4, inclusive, exerts a sufiicient pull thereon after the target is released from the carrier. By this means successive targets may slide by means of their coupling members down the tow cable to ultimately engage the snap hook I52 to couple the target in towing relation to the cable. The means for explosively releasing the target will be subsequently described.

Emergency cable release By reference to Fig. 8 it is seen that the inner end of the tow cable I50 is provided with a ball terminal I51 which is releasably seated in an aperture I58 formed in a member I60 secured to and inwardly projecting from the winding drum I I6. Member I60 is provided with a further aperture I6I in which is mounted a spring pressed latching lever I62 pivotally supported at I63 and having a latching detent I64 adapted to engage a pivotally mounted catch I65, which upon release will allow a latching member I62 to rotate about its pivot I63 releasing the ball terminal I51 to allow the same to emerge from member I60 and thus release the cable from connection to the winding drum. The catch I65 is adapted to be actuated by means of a plunger I66 which is urged by a spring I 61 from engagement with the catch member I65. Plunger I66 sliolably mounted in the ring member II5 has its outer end I68 rounded off and normally projecting from the side of the winding drum but out of engagement from a tripping member I69 formed as a cam on the end of a rod I10 slidably mounted in a suitable bearing in the end frame member I02. The rod or plunger I10 is pivotally connected to a bell crank I1I which, as seen in Figs. 9 and 10, is connected to the plunger I 12 of an actuating solenoid I15 which is secured by means of a removable bracket I16 to the end frame I02. It will be clear from Figure 10 that when the solenoid I15 is energized the plunger I12 will rotate the bell crank HI and plunger I10 to move the cam actuator I69 outward so that the same will be engaged by the rounded tip I68 of plunger I66 pushing the same inward to actuate catch member I65 and thus release the ball I 51 from its retaining socket 58 and free the tow cable I59 from connection with the winding drum. The solenoid I15 is adapted to be energized by means of an emergency control which will be described in connection with description of the wiring diagram.

By again referring to Fig. 6 it will be seen that the shaft I31 has mounted on its free end a sprocket I which is adapted to drive chain I8I to in turn drive a sprocket I82 and shaft I83 which is externally threaded and adapted by I85 actually is operated slightly before the cable I is completely wound in. Motor overrun takes care of the remainder of the winding operation.

Fig-l1 illustrates the construction of'one of the explosive connecting rings C1, etc, employed to connect a tow target toth e tow cable. The g body C1 of the connector is madeof a molded plastic insulating material such as nylon in the form of a ring with a pair of metallic conductor segments I86 and I89 secured to the inner periphery of the ring. A pair of electricallyignited explosive cartridges I8? are imbedded in the ring C. The cartridges I8? are'provided with internal spark'gaps not shown and each is electricallyconnected to. one of the segments I89 and lad-and further connected in series by means of a conductor I98. The conductor segments I99 and I96 are shunted by means ofa leakage resistor I89 which prevents the collection of static on the tow cable from exploding the cartridges. In use the. tow target bridle such as B1 (Fig. '7) engages one of the conductor segments such; as I99 while segment I855 will beengaged by the hook I52 on the 'tow cable. When the tow cable is energized by a potential of from fourteen to thirty thousand volts,.the distributed capacity between the tow cable andthe target is suflicient to permit sparks to jump the gaps in the cartridges I81 exploding the same. I 3 1 The explosionof the charges in cartridges I91 burststhe connector ring which permits the target-and bridle to become" disconnected from the l tow cable and the weight. of the tow hook I52- issufficient to maintain the cable v I 99 sumciently loaded to enable it to be reeled in.

It is noted that the foregoing description-of the construction of the explosive connecting rings adapted to release tow targets does not per se form any part of the present invention and is disclosed and claimed in the copending application of James P. Welshand' John L. Jewett, Ser. No. 20,634, new Patent Number 2,499,912, which is assigned to the Government of the United States;

' Generdl uii rz'ngd'iayram Referring to 12 which illustrates the gen lower contact I93 of a power relay generally indicated at I95, the contact I93 and a similar upper contact I94 being adapted to engage contacts connected to'conductors I96 which supply current to the winding motor I05, previously described. Contact I94 is connected to ground to form the return side of the system, and upon actuation of relay I95 motorv I05 will be'energized to reel in the tow cable.

Conductor I9l has abranch conductor I98 connected thereto and also is provided with an overload release I99 and a push-button switch 299 connected in a series therewith. A-holding relay, generally indicated by reference numeral 29 I ,.has its coil connected to conductor I93 beyond the push button 260 and is operative such that when the coil is energized the normally open contacts of the holding relay shunts the switch 299, to

complete a circuit irrespective of whether the switch299 is thereafter released. The coil of relay so! isconnected to the normally closed contacts of a normally inactive relay 292, the contacts of which are connected to a conductor 203 which is connected to the normally closed contacts of a normally inactive relay 29:; and from thence by means of conductor 295 to the contacts of a normally inactive relay 299 and from thence to ground by means of a conductor 29?. It will be understood that, upon operation of push button 299 a circuit will be formed through holding I relay 29I,. the contacts of relay 292, conductor 293, contacts of relays Z94 and 299 toground'so that current may continue to flow through the shunt around push button 290 into conductor I 98. After push-button 299 is released conductor I98 is connected to th coil of relay 209 which in turn is connected to the conductor 24! which may be connected to ground'through a number of sepa- I rately actuated switches later to be described for the purpose of breaking contact between thenormally closed upper contacts from relay 299 to release the holding relay 29L Conductor I98 has a signal lamp 298 connected thereto and to ground such that whenever the push-button 299 is actuated and holding'relay 21H completes a circuit signal lamp 298 will be energized. The conventional step-by-step' relay, generally. indicated at 2H], is connected in paralleltothe conductor I99 and has its actuating Icoil-2II con nected through a normally closed switch '2I2 to ground so that each time the push-button 299 completes a circuit through conductor I98 coil 21! will be energized. The switch 2I2 is shunted by'means of a resistor 2I3 so that when the sole- .noidplunger member 2 I9 is actuatedby energizing coil H I, switch 2 I 2 is opened and current flow through the relay coil 2| I is reduced'to minimum value, by means. of the resistance 2I3 being directly in series therewith, thus preventing the step-by-step relay from overheating. The relay solenoid plunger2l4 actuates a star wheel BIS through the arcuate distance of the spaceof one tooth each time the plunger 2 I 9 is moved to cause a, corresponding step-by-step rotation of the shaft 2 I6 which is connectedto a switch arm 2 I9. The

switch arm M8 is adapted to engage a respective one of a plurality of radially arranged contacts seriatim each time the star wheel I25 is rotated. Switch arm 2 I3 is directly connected by means of conductor 2| 9 to the conductor I98 to receive current therefrom and to deliver current to the respective step-by-step relay contacts which are arranged in parallel. connected groups. All'of the switch contacts indicated by reference character R are connected in parallel and operative to initiate the target releaseoperation and similar spaced parallel connectedcontactsindicated by reference character W controlling the winding operation and other spaced contacts indicated by the reference characters D1 to D4, respectively,

controlling discharge of respective targets. The

relay contacts are so arranged that they fall in the sequence 'D1R--W, D2R-W .etc. Each time the step-by-step relay 2 I 9 is actuated switch 1 1 contact 2 I8 is moved in a clockwise direction from one contact to th nextand the relay operating time of all of the relays employed in the system are so arranged with respect to the operating time of the relay 2 I that the switch arm 218 can move from its last engaged contact to the succeeding contact without causing operating of the vcomponents of the system.

A1l of the contacts indicated by referencecharacter W, there being four in number, are connected in parallel by means of a conductor 220 which in turn is connected by 'means of a conductor 22l to the coil of relay 206 which in reference character R are all connected in parallel to a conductor 225 such that when the switch arm 218 engages any of the R, or release contacts, current from conductor 158 through conductor 2 l0 and the switch arm 2 l 8 will energize the conductor 225 which in turn will energize the coil of a relay generally indicated at 226 to cause the relay to close normally open contacts 221 and to complete a circuit through conductors 228 to start up the motor unit of a conventional motor generator set or inverter, not shown, the generator of which delivers four hundred cycle alternating current through conductor 232. A conductor 229 connected in parallel to conductor 225 is energized concurrently therewith and delivers current through a normally closed switch 231 to the coil of arelay 230 and thence to ground to thereby actuate the relay so that the contacts-thereof complete a circuit from conductor 232 to the primary of a high-voltage autotransformer generally indicated by reference numeral .234. Switch 23l'is a protective switch which is opened whenever the insulating cover [8 (Fig. '1) is removed. The high-voltage secondary of the transformer 234 is connected through the cable drum and contacting parts directly with thetow cable I56 such that when the transformer primary is receiving four-hundred cycle alternating current from conductor 232, the secondary delivers a potential of from fourteen to thirty thousand volts, with respect to ground to tow cable I50 for the purpose of explosively releasing a connected targetes will be subsequently described. Conductor 225 is connected directly to the upper terminal of the coil of relay 202 which is normally inactive through a normally open thermal switch 235 to ground and the coil of relay 202 is shunted by means of a control potentiometer 231 and heater resistance 236 for the switch 235 such that while conductor 225 is conducting current, heater 236 heats the thermal switch 235 such that the same closes after a predetermined time such as five seconds. When thermal switch 235 is closed the coil of relay 202 is energized to break the circuit through its normally closed contacts from holding relay 20! to conductor 203 and thus opens the circuit through conductor 198 to thereby'deenergize conductor 225 and relay 226 to shut down the inverter connected to conductors 228 and 232 and causing the tow cable I50 to be electrically deenergized.

When the step-by-step relay switch arm 218 contacts the switch contact D1 a circuit is completed from bus conductor I98 to conductor 245 and the coil of door release solenoid 26, Fig. 4, to release the door 10, Fig. 2, and allow the target housed in the lower right-hand compartment of Fig. 3 to be discharged by gravity. As soon as the door 10 (Fig. 2) is opened through an angle of fifteen degrees a switch 246 is actuated by the door closing a circuit from conductor 241 toground. Current then flows from conductor I98 through the coil of relay 204 and conductor 241 energizing the relay and breaking the circuit through its contacts and conductors 203 and 205 and thus deenergizing the holding relay 20l which deenergizes the system including door release solenoid 26.

When relay switch arm 218 engages the contact D2 current is conducted from the switch arm and contact through .a conductor 248 to the coil of door release solenoid 26a which forms a part of the release assembly 25, Fig. 3, and causes the release of door 10 to effect discharge of the target T4; Movement of door [0, Fig. 3, through an angle of fifteen degrees effects actuation of a switch 249 to connect conductor 241 .to ground and by energizing relay 204 effects deenergizing a holding relay 20! opening the circuit to the coil of release solenoid 26a and renders the system electrically dead.

When the switch arm 218 engages contact D3 the conductor 210 is energized to complete a circuit through relay armature contact 213 of a relay, generally indicated at 212, to complete a circuit through conductor 214 to energize the coil of the inner door release solenoid 66 of the release solenoid assembly 65, shown in Fig. 5, thus allowing the inner partition door [5 to drop permitting target T2 to fall from the upper compartment of container 4 into engagement with outer release door 10. Movement of the inner partition door l5 in Fig. 2 through an angle such as thirty degrees causes a switch 215 to be closed completing a further circuit from conductor 210 to a conductor 216and the coil of relay 212 to ground. Relay 212, upon being energized, opens the contacts at 213 and breaks the circuit through conductor 214 deenergizing door release solenoid 66, but in so doing engages further contacts to complete a circuit from conductor 210 to conductor 245, thus energizing the coil of release solenoid 26 causing door 10, Fig. 3, to be released and to open due to the weight of target T2 resting thereon, and permitting the gravity discharge of the target in the same manner as previously described. Opening movement of door I0, Fig. 2, again actuates switch 246 to energize relay 204 and to open the circuit through holding relay 201 to deenergize the system in the manner previously described.

When relay 212 is energized lower contacts thereof complete a holding circuit through its coi1 to maintain the relay energized until the holding relay 201 is deenergized by actuation of switch 246 in the manner above described.

Engagement of step-by-step relay switch arm 218 with contact D4 energizes a conductor 250 which through the upper parallel connected contacts of a relay 252 energizes a conductor 253 to actuate the release solenoid 66a to release the inner partition door l5 of Fig. 2, allowing an inner target T3. Fig. 3, to be dropped into engagement with lower door 10. Movement of the partition door 15 actuates a switch 254 to complete a further circuit from conductor 250 to a conductor 255 to energize the coil 266 of relay 252 previously described.

In order that the pilot may be at all times aware of the operating condition of the system there is provided as seen in Fig. 13 a' panel 288 on which is mounted a dial 282 having indicia angularly spaced thereon indicative of the last operation performed and a pointer 283 adapted to cooperate with the indicia and actuated by an extension of the shaft 2% of the stepping relay 2I I which is mounted on the back of the panel. The main control push button 209; the emergency push button and the signal lamp 2&8 are also mounted on the as well as the master switch and circuit breaker I92 an'd'the auxiliaryswitch and circuit breaker E99. Each-time push button 2% is actuated signal lamp 208 will be illuminated and as the steppingrela'y 2II (Fig. 12). indexes the switch arm '2 i ii the shaft 2 IE will also position the pointer 283 relative the indicia'on dial 282 to indicate the operation being performed.

Although the operation of the system has been described with respect tothe generalwiring diagram a further detailed description of the sequence of operation will now be described. With reference to Fig. 14 it willbeassumed that the step-by-step relay switch arm 2 I 8 was last at rest on the contact W immediately abovecontact D1 as seen in this figure. or the first target the pilot then-closes pushbutton switch 298 whichenergizes conductor I98 and illuminates signal lamp 208 and energizes the armature winding 2H of the step-by-step relay 253, causing the armature 2I4 to move downward and rotate the star wheel 2 i 5 through the space of one ratchet tooth moving switch arm 253 onto contact D1. In the meantime cloof push-button switch 280 completes a circuit through relay 2i! i, the upper contactsof relay 2&2, conductor 2%, upper contacts of relay 2% conductor 2%, contacts of relay 206 and conductor 2%? to ground as previously described; The 2M will thus be energized to complete a shunt holding circuit around push-button 209 so that release of the same will not interrupt the circuit through conductor. I98. Rotation of switch arm 2Iil 'onto contact D1 completes a circuit from conductor I98 to conductor are through theswitch arm 2H3, contact Dr to conductor 245 to the coil of door release solenoid 26 to release the lower door I0, Figs. 2 and 3, as previously described. Release of the lower door it permits gravity discharge of the first target from the target carrier 2. Release of the target In order to effect discharge energized and breaking gen-as 203 in conduct r its causing homing relay 2m to become deenergized and thus deenergizing the system.

After the first target is in tow and it is desired 7 to release the same to provide for targetexchange the operation of target release is next in order and the circuit components of Fig. 12 effective therein are shown in Fig. 15. Referring" to this figure the pilot again operates push button 2% through the normally closed protective switch 23E through the coil of relay 23G causing the contacts or the same to complete the circuit from conductor 232 to the primary of high voltage transformer 233. High voltage output fromthe secondary of transformer 23 i energizes the tow cable i5il to explosively rupture the frangible coupling C as described with reference to Fig; 11 and causes the first tow targetto be disconnected from the tow cable and droppedv to the ground to be subsequently retrieved; After the inverter has built up full voltage supply to the primary of transformer. 234 heater coil 236 heats the thermal switch causing the same to close after a predeterminedtime interval of say five seconds as determined by the setting of the potentiometer 23? which. causes the coil of relay 292- to become 7 the holding circuit through the contacts thereof vfrom holding relay 2!]! thus deenergizing the system as previously explained.

After release of the first target the pilot causes the cable to be reeled in which operation the circuit components of the wiring diagram, Fig. 12, such as illustrated in Fig. 16 become effective After the release operation the next actuation of pushbutton 20!] causes the stepping relay 2I I to move the switch arm MS from the release or R contact to the succeeding W contact and at the same time establishes a holding circuit through holding relay Zill in the manner as previby gravity'allows the same to be blown rearward by the air stream causing'the bridle B toslide the connector C off the guide I49 (Fig. 7) to engage the tow hook I52 and pull out the tow cable until the same is all unreeled.

Release oi?! the door Ill causes actuation of switch 236 after'the door has moved through an ously. described. I

a Current from conductor I Sdflows through conductor 220 connected in parallel with the contacts W and by. meansof conductors 22! and 223 energizes relay to complete 'a circuit from bus bar i9! through winding motor I65 to ground. The motor Iii5then actuates' the reel I IE to wind in the toW cab1e 55f] (Fig. 8).

When a predetermined amount of tow cable has been reeled the normally open footage switch I closes completing a circuit from conductor 22l through relay 206 to ground and causing the same manner as in the discharge of the first tar.

et describ ed above.

The operations of target release and cable rewind next precede the release of the third target, Fig. 1'7, which is efiected when the stepping relay moves the switch arm onto the contact D3 which energizes conductor 21!], upper contacts 273 of relay 2'12 and conductor 216 which energizes the door release solenoid 66 which drops the inner partition door 15, Fig. 2, and permits the target supported thereby to drop into contact with the outer door Ill, Figs. 2 and 3. Movement of the partition l5 through an angle of fifteen degrees closes a switch 215 which connects conductor 21!] to conductor 216 and energizes the coil of relay 212 causing the contact at 273 to be broken and conductor 210 connected to conductor 245 through the relay contacts. The door release solenoid 26 then is energized to release the outer door Ill, Fig. 2, permitting the third target resting thereon to be discharged. Movement of the door [0 actuates the switch 246 which completes a circuit from conductor I98 through relay 264 causing the same to break the holding circuit from relay contacts of relay 202 and conductors 203 and 205 to ground thus deenergizing the system.

After discharge of the third target and the subsequent operations of target release the fourth target is discharged in which door release solenoids 66a and 26a are sequentially operated in the same manner as above described with refera.

ence to discharge of the third target.

At any time when the tow cable is extended the same may be released by pressing the emergency push-button switch 240 which energizes the emergency cable release solenoid I15 to release the cable in the manner described above with respect to the wiring diagram, Fig. 12.

Although one embodiment of the invention has been illustrated and described variations thereof will be apparent to those skilled in the art as coming within the scope of the invention as defined in the appended claims.

I claim:

1. Apparatus for towing aerial targets from high speed aircraft comprising a streamlined container adapted to be suspended from the towing aircraft and having means for housin a plu rality of aerial tow targets therein, releasable discharge doors on said container, a braked power driven reel positioned in the rear portion of said container and having a tow cable positioned thereon, a towing hook on said cable, a cable guide associated with said reel and having the tow cable passing therethrough, said guide having means for supporting a plurality of electrically releasable target coupling devices thereon each connected to the towing bridle of a respective tow target, and an electrical remote control system adapted for sequential actuation by the aircraft pilot to operate the discharge doors to discharge a target from said container into the air stream to thereby cause the associated coupling device to engage the tow hook and withdraw the towing cable against the braking resistance of the reel, to electrically actuate the coupling device to release the coupled tow target and to energize the reel driving mechanism to reel in the extended towing'cable, said electrical control system being conditioned upon completion of each cycle of target discharge, release and cable reeling operations to be operative to repeat such cycles until all of the targets have been discharged and released.

2. The structure as claimed in claim 1, in which said power driven reel is provided with releasable means for connecting one endof the tow cable thereto, said releasable means including remotely controlled actuating means operative during rotation of the reel to disconnect the cable therefrom.

3. In a tow target system of the character described a target housing comprising a streamlined container having an opening in the bottom thereof for gravity discharge of targets therethrough, closure means normally closing said opening and provided with retracting means and latch means for maintaining said closure means in the closed position, internal hinged partitions in said housing serving to support tow targets resting thereon, individual latch means holding each of said partitions in target supporting position, electrical control means for the closure latch means and the respective partition latch means, said control means being sequentially operative to release said closure latch means to discharge a tow target initially resting thereon and to first actuate a respective partition latch means to drop a target resting thereon onto said closure means and thereafter to actuate the closure latch means to discharge the target from the container.

4. In a high speed aerial tow target system of the character described, a means for housing a plurality of aerial tow targets including an opening for the gravity discharge of targets therethrough, closure means for said opening, means for actuating said closure means to the open and closed position permitting selective discharge of targets, a power driven reel having a tow cable thereon, said cable having a tow hook at the end thereof, a guide having the tow cable passing therethrough, a plurality of electrically exploded frangible couplings positioned on said guide, each of said couplings being connected to the towing bridle of a respective target, each target upon discharge into the relatively moving air stream causing the coupling member associated therewith to pass off the guide and engage the hook on the tow line and means for electrically exploding a connected coupling to release the coupled target, said reel being subsequently energized for reeling in the tow cable for connecting a new target.

5. A tow target system as claimed in claim 4, including electrical circuits operative for energizing said closure actuating means, said explosive couplings and said reel, a selector switch operative to sequentially connect said circuits to a power source in a predetermined order and a control switch adapted for actuation by an occupant of the aircraft for actuating said selector switch.

6. The structure as claimed in claim 5 in which indicator means are provided actuated in unison with the selector switch to give a continuous indication of the operation last performed.

'7. A system for high speed aerial towing of targets comprising means for housing a plurality of aerial tow targets, means for selectively and sequentially discharging said targets into the relatively moving air stream, a power driven reel operatively associated with said housing means and having a tow cable thereon adapted to be unreeled by aerodynamic drag force of a connected target and to be reeled in to effect target exchange, a towing hook on said cable, a guide means concentric with said cable, a plurality of electrically exploded frangible couplings mounted on said guide each connected to a respective tow target and adapted to be removed from said.

17 guide by drag of an associated target into coupling engagement with the tow cable hook and means for electrically energizing the tow cable to cause ignition and explosive disruption of a connected coupling to release a target being towed. I

8. A carrier for aerial tow targets comprising a streamlined housing for housing a plurality of tow targets, a discharge opening in said housing, closure means for said discharge opening and having release means permitting said closure means to open due to the weight of a target resting thereon, hinged partitions in said housing serving as supports for respective targets, releasable latches for each partition permitting the partitions to drop so that individual targets may be dropped to rest on said closure means, means for actuating the closure release means, means for actuating the respective partition latches and means for interlocking said last two named means for sequential operation.

9. Apparatus for high speed aerial towing of targets comprising a means for housing a plurality of tow targets, a reel having a tow cable wound thereon and having braking means permitting the tow cable to be unreeled at a slow rate by tension load due to aerodynamic drag of 18 a connected target, power means for driving the reel to wind in the cable, means for discharging the targets individually from said housing means, a coupling device connected to each target and adapted to automatically connect to the end of the towing cable upon discharge of the target into the air stream, each coupling device includ- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,183,540 Campbell Dec. 19, 1939 2,460,194 Schultz Jan. 25, 1949 

